1. Field of the Invention
The present invention is directed to improved optical sensor locations in the product meter of an air seeder.
2. Description of the Prior Art
Air seeders are commonly towed by tractors to apply seed and/or fertilizer to a field. As an example, an air seeder may be towed in combination with a tilling implement, one behind the other, to place seed and fertilizer under the surface of the soil. An air seeder has as its central component a wheeled seed cart which comprises one or more frame-mounted product tanks for holding granular product, such as seed and/or fertilizer. Air seeders are also provided with product meters associated with each product tank for dispensing metered product from the respective product tank into a pneumatic distribution system for delivering the metered product to the field.
Typically, air seeders are provided with volumetric meters which measure a fixed volume of granular product per unit of linear distance. These volumetric meters typically comprise either augers or fluted cylinders (meter rollers). The product meters rotate to feed metered product into a pneumatic distribution system. The pneumatic distribution system of an air seeder generally utilizes a blower to provide at least one airstream which flows through the pneumatic distribution system to seed boots where product is deposited in the soil. Metered product is introduced into the air stream at a primary air distribution manifold located below the product meter. Product is carried by the air stream through distribution lines to a series of secondary distribution manifolds ("headers"), which in turn distribute product through individual lines to seed boots mounted behind ground openers on the tilling implement.
Current air seeders do not provide a method of sensing product flow in the meter. For positive pressure air systems, the product tank of the air seeder must be pressurized to meter product correctly. When pressure is lost in the tank, the flow of metered product would be slowed or even stop. Current sensors sense product flow downstream from the manifolds. In applications where two products from two separate tanks are metered into a single rank of tubes at different locations, the product flow from individual meters cannot be sensed because of the product meters being connected to the same air lines. One meter can stop metering while others continue to function properly thus giving no warning to the operator that the flow of one product has stopped or slowed because of the continual flow of product from the other meters.